Electrical amplifying circuit



July 28, 1936. H. HERTWIG ET AL 2,049,376

' ELECTRICAL AMPLIFYING CIRCUIT Filed Dec. 6, 1932 y I? f Inventors Hafry i lertwig,

Helmut Hintze,

Their Attorney.

Patented July 28, 1936 UNITED: STATES PATENT OFFICE Hintse, Berlin-Wendenschlosa,

Germany, as-

aignors to General Electric Company, a corporaflon of New York Application December 6, 1932, Serial No. 846,018 In Germany December 21, 1931 8 Claims. (CL 250-415) Our invention relates to electrical amplifyin circuits and concerns particularly arrangements for causing the operation of electrical devices in response to impulses which are either too weak or of too short duration to cause the operation oi said electrical devices directly.

It is an object of our invention to provide a simple, reliable, and easily constructed device for amplifying or for counting relatively short or weak electrical impulses. Other and further objects and advantages will become apparent as the description proceeds.

In accordance with our invention in its preferred form, we utilize anelectrical valve, preferably a vapor-discharge tube having a control grid to control the flow of current in an electrical device in response to relatively short or weak impulses. The control grid is normally'negatively biased and the apparatus is so arranged that the potential of the control grid is caused to-rise in response to an impulse, thereby initiating a discharge in the discharge tube. The discharge having been initiated then continues for a length of time sufficient to operate the electrical device even though it be relatively slow acting. The discharge is then automatically terminated, restor-= ing the apparatus to a condition for the reception of the next impulse.

The features of our invention which we believe to be novel and patentable are pointed outin the claims appended hereto. A better understanding of our invention, however, may be obtained by referring to the following description taken in connection with the accompanying drawing in which Fig. 1 represents schematically the electrical circuit of one embodiment of our invention, and Fig. 2 represents a modification thereof.

Referring now more in detail to the drawing in which like reference characters refer to like parts throughout, we have illustrated the application of one embodiment of our invention to the operation of electrical counting devices, but it will be understood that this example is given merely by ,way of illustration and our invention is not limited thereto.

A discharge tube ll of the gas or vapor-filled. type having a control grid l2 and having an anode l3 and a cathode it connected respectively to the positive and thenegative sides of a source ofcurrent i5 controls the operation of counting device It having an actuating coil I1 connected in series with the current source l5 and the discharge /tube II. The discharge tube I l is oi the type well known in the art in which the discharge initiated by raising the potential of the control grid I2 to a suiiicient value continues thereafter irrespective of the grid potential until the anode potential falls below a value dependent upon the characteristics of the tube and referred to herein as the de-ionization potential. Discharge tubes of this type are referred to hereinafter as vapordischarge tubes, and it will be understood that we mean to include by this expression all discharge tubes of the type just described whether their action is due to the presence of inert gas, metallic vapor, or other gases, vapors, or mixtures thereof.

A suitable device or element having the characteristic of changing materially in resistance without the absorption of appreciable energy and preferably responding with relatively great rapidity, such as a photo-electric tube It, is connected in series with a resistor i9 and a source of electromotive force such as a battery betweenthe anode and the cathode ll of discharge tube Ii. The battery 20 has its positive terminal connected 20 to the cathode i4, and the relationship between the resistance of resistor i9 and the normal resistance of the device i8 is such that the control grid i2 is normally maintained at a negative potential with respect to cathode I4, and the discharge tube l l is therefore normally non-conduct ing. In the form of apparatus illustrated, the photo-electric tube i8 is exposed to the radiation of a lamp 2 I, and responds to light impulses produced by momentary illumination of the lamp or to current impulses in the lamp filament which cause it to become illuminated. It will be understood, however, that if some form of variable resistance device l8, other than a photo-electric cell is to be employed it will be suitably arranged .to respondto the desired impulses, the exact nature of which does not form a part of our invention.

In order that the discharge in tube ll may be self-extinguishing after current has flowed through winding i1 long enough to operate the device It, there are provided elements which may take the form of a resistor 2| connected in the anode circuit of the discharge tube ii and a condenser 22 connected between the anode II of the discharge tube H and the negative terminal of thecurrent source is. The winding ll of the device It is inherently inductive and we find that the most satisfactory results are obtained by keeping the resistance of the circuit formed by the discharge tube ll, inductive winding i1, and condenser 22 at a value sufliciently low to make the circuit li-Il--22 oscillatory. This may necessitate using a relatively low resistance winding ll. However, an equivalent result may be 55 obtained, as shown in Pig. 2, by substituting an inductance 23 for the winding i1 and connecting the winding ll of the device it in one oi the leads oi. the source Ii. i

In the operation 0! our device, the occurrence of an impulse causes the resistance 0! the device i I (in the arrangement shown, a photo-electric tube) to fall to such a value that the current begins to flow through device l8, resistor i9, and battery 20, from the connection to anode it to the connection to cathode ll. The relationship between the resistances oi device it and resistor II is then such that the potential drop in resistor il raises the potential of the grid I! to a value at which the tube ii becomes conducting. 01rrent then begins to flow from current source ll through discharge tube ii and winding II, the action being the same whether winding i1 is connected in the position shown in Fig. 1 or the position shown in Fig. 2. Owing to the character of the discharge tube ii, current continues to flow in the winding i! even though the impulse aii'ecting device I! may have ceased, and the potential of grid i 2 may have fallen again to its normal negative bias. The "continuance ot'the current through winding il permits the operation 01 the device it, which may be of the slowacting type or of a type which would not respond to the shortness of the impulse aiiecting device II. The constants oi the resistor 2| and condenser 22 are so chosen that when discharge tube ll becomes conducting, condenser 22 becomes partially discharged and thereupon the potential drop in resistor 2i causes the anode potential of the tube ii to fall below the de-ionization potential of the tube, extinguishing the discharge after suflicient current has flowed to Operate the device ii.

In accordance with the provisions of the patent statutes, we have described the principle of operation 01E our invention, together with the apparatus which we now consider to represent the best embodiment thereof, but we desire to have it understood that the apparatus shown is only illustrative and that'the invention may be carried out by other means.

What we claim as new and desire to secure by Letters Patent 01 the United States is:

l. A device for counting impulses of short duration comprising a vapor-discharge tube having an anode, a cathode, and a control grid, a source of direct current, aresistor connected between the positive terminal of said source and the anode of said discharge tube, a condenser connected between the anode of said discharge tube and the negative terminal of said source, an electrical counter having an actuating coil with inductive characteristics connected between the negative terminal of said source of current and the cathode of said discharge tube, a photo-electric tube having a pair of terminals one or which is connected directly to the anode of. said dischargetube, a

source of electromotive iorce having a pair of terminals, the positive or which is connected to the cathode of said discharge tube, a resistor of relatively high resistance connected between the remaining terminal of said photo-electric tube and said source of electromotive force, the control grid of said discharge tube being connected directly to the common terminal of said photoelectric tube and said last mentioned resistor so as to be normally negatively biased, and means for illuminating said photo-electric tube in response to said impulses, thereby causing said photo-electric tube to become conducting permitting the potential of the control grid of said discharge tube to rise and to cause said discharge tube to become conducting, thereby causing a current to flow through the actuating coil 0! said electrical counter so as to cause a poten- 5 tial drop in said first-mentioned resistor, reducing the anode potential oi said discharge tube below the de-ionization potential and terminating the discharge of said tube after an interval sumcient to operate said electrical coimter. l0

2. A device for counting impulses oi short duration comprising a vapor-discharge tube having an anode, a cathode, and a control grid, a source of direct current, a resistor connected between the positive terminal 0! said source and the anode 15 or said discharge tube, a condenser connected betwem the anode of said discharge tube and the negative terminal oi said source, an electrical counter having an actuating coil connected in series with said source of currmt and said discharge tube and an inductance connected between the negative terminal of said source and the cathode or said discharge tube, an impulse-responsive device of variable resistance having a pair 01 terminals, one 01' which is connected directly to the anode of said discharge tube, a source of electromotive force having its positive terminal connected to the cathode 0! said discharge tube, a resistor oi relatively high resistance connected between the remaining terminal or said impulseresponsive device and said source of electromotive force, the control grid 0! said discharge tube being connected directly to the common terminal of said impulse-responsive device and said last-mentioned resistor so as to be normally negatively biased, said impulse-responsive device being arranged to tail in resistance in response to said impulses, thereby permitting the potential oi the control grid oi said discharge tube to rise and to cause said discharge tube to become conducting, allowing a current to flow through the actuating coil 0! said electrical counter so as to cause a potential drop in said first-mentioned resistor, reducing the anode potential of said discharge tube below the tie-ionization potential and terminating the discharge 0! said tube after an interval suflicient to operate said electrical 3. An electrical circuit responsive to impulses r oi. short duration comprising a vapor-discharge tube having an anode, a cathode, and a control grid, a source of a direct current, a resistor connected between the positive terminal oi said source and the anode of said discharge tube, a condenser connected between the anode of said discharge tube and the negative terminal oi. said source, an inductive device connected between the negative terminal oi said source and the cathode of said discharge tube, the electrical dimen- M slons of said discharge tube, condenser, and inductive device beingsuch that the circuit formed thereby is oscillatory, a device which falls in resistance in response to impulses and having a pair of terminals, one of which is connected directly as to the anode 01' said discharge tube, a source of electromotive force having a pair oi! terminals, the positive of which is connected to the cathode of said discharge tube, a resistor of relatively high resistance connected between the remaining terminal of said variable resistance device and said source oielectromotive force, the control grid 01 said discharge tube being connected directly to the common terminal of the variable resistance device and said last-mentioned resistor so as to be normally negatively biased, whereby anode potential of said discharge tube below the the occurrence of an impulse causes said vade-ionization potential and terminating the disriabie-resistance device to fall in resistance percharge of said tube after an interval sufllcient mitting the potential of the control grid of said to operate said inductive device.

discharge tube to rise permitting a current to flow in said discharge tube so as to cause a potential HARRY HERTWIG. drop in said first-mentioned resistor, reducing the HELMUT HIN'IZE. 

